What Is Cushing’s Disease In Dogs?

If you’ve heard of Cushing’s disease before, you’ve probably heard about it as a human disease.

But did you know dogs can get it too?

Whether your pup has recently been diagnosed or whether you’re just curious if he might have it, you probably have a lot of questions — like what is Cushing’s disease in dogs, how do dogs get Cushing’s disease and what are the symptoms?

The Dodo spoke to Dr. Bernadine Cruz, a veterinarian at Laguna Hills Animal Hospital in California, to find out everything you need to know about Cushing's disease in dogs.

Cushing’s disease — also known as Cushing’s syndrome — is a condition that occurs when your dog’s body isn’t making the right amounts of certain hormones.

“Cushing’s syndrome ([aka] hyperadrenocorticism or HAC) is an overproduction or presence of cortisol, a steroid, in the body,” Dr. Cruz told The Dodo.

Cortisol is a stress hormone produced by animals, including both people and dogs. It serves a lot of purposes in the body — including controlling weight and blood sugar and fighting infections.

So when it’s present in your pup in an irregular amount, it can cause a pretty wide range of symptoms.

Cushing’s disease can occur naturally, and there are two major types: pituitary dependent and adrenal dependent. (Heads up that the distinction between the two is a little complicated.)

The most common type is pituitary dependent, and about 80 percent of dogs with Cushing’s disease will have this type. This type is caused by a tumor on the pituitary gland located in the brain.

“[Pituitary dependent Cushing’s] is considered [to be] an endocrine disease due to both adrenal glands becoming hyperactive and releasing an inappropriate amount of cortisol,” Dr. Cruz said. “This is due to a defect in the feedback mechanism between the adrenal glands and the master controlling pituitary gland in the brain.”

Adrenal dependent Cushing’s occurs when there is a tumor on one of the adrenal glands on the kidneys. This is a bit rarer than pituitary dependent, and only about 15 percent of dogs diagnosed with Cushing’s will have the adrenal dependent type.

Dogs can also develop a version of Cushing’s syndrome called iatrogenic Cushing’s syndrome, which is caused by certain medical treatments — particularly an overuse of steroids.

“It can also be introduced by the oral administration or topical application of steroids, as can occur when pet owners of itchy pets administer too many steroid pills or apply topical steroids too exuberantly over an extended period of time,” Dr. Cruz said.

While any dog (or cat) can contract Cushing’s, the disease is most common in middle- to older-aged dogs. Certain breeds are also at higher risk, including beagles, Boston terriers, dachshunds, German shepherds and poodles.

“The most characteristic sign that a pet owner will observe is drinking an increased amount of water and increased urination,” Dr. Cruz said.

Other symptoms include:

Cushing’s syndrome in dogs typically has a long onset — which means symptoms may come on gradually rather than appearing overnight.

“This is one of the reasons why pets should have routine physical examinations (at least once a year — pets over 7 years of age should be seen twice yearly) and routine blood [and] urine work should be analyzed,” said Dr. Cruz.

“Diagnosis can be tricky. There is no one test that is 100 percent accurate,” Dr. Cruz said. “A routine blood chemistry screen may show elevated liver enzymes (especially alkaline phosphatase), elevated cholesterol and increased blood sugar (hyperglycemia). Increased amounts of protein can be detected in the urine.”

If results from blood and urine tests show potential signs of Cushing’s, your vet will likely perform additional hormone screening tests: an ACTH stimulation test and a low-dose dexamethasone suppression (LDDS) test.

According to Dr. Cruz, “radiographs may be needed to help rule out other conditions, along with ultrasounds, CTs and MRIs, depending on what is noted by the veterinarian.”

Imaging will help your vet to see if there is a tumor on the adrenal glands or pituitary gland, which will determine what kind of treatment is needed.

That may all sound really complicated and technical, but the takeaway is that it might take a while for your vet to definitively confirm your pup has Cushing’s disease.

Cushing’s disease is a serious condition and will require you to work very closely with your vet to find a treatment solution that works for your pup. If Cushing’s goes untreated, it can be fatal, which is why it’s so important to watch out for any symptoms and to take your pup for regular checkups, since an early diagnosis will help your dog’s long-term prognosis.

Treatment will depend on your dog’s specific type of Cushing’s, as well as his overall health. If your dog has a tumor on his adrenal glands, your vet may be able to remove the tumor. But this isn’t always an option.

If your dog has a malignant tumor on either the pituitary or adrenal glands, the prognosis is not as good, and he might need additional treatment. Malignant tumors should be treated as soon as possible for the best outcome, Dr. Cruz said. But most of the time with Cushing’s, tumors are benign (not cancerous — phew!).

Cushing’s caused by steroid medication can be treated by gradually stopping the steroids, but that means the original condition that was being treated by steroids will probably come back, so you’ll have to find alternative treatments.

There is no “cure” for Cushing’s disease, so in most cases, your dog will need to go on medication for the rest of his life.

“Lifelong therapy is typically needed,” Dr. Cruz said. “Which medication is chosen is a function of the general condition of [your] pet and concomitant medical conditions.”

While Cushing’s is a lifelong condition, your pup can still live a relatively normal life if you follow your vet’s treatment plan.

“With a good response to medication, a stringent adherence to recommended follow-up exams and lab testing and a bit of good luck, a dog can live for years with this condition,” Dr. Cruz said.

Your pup will need to take medicine for the rest of his life, but the good news is it’s a pretty manageable condition as long as you follow your vet’s advice!